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Aim: Woody ecosystems provide critical ecosystem functions and services but are increasingly threatened as invasive pathogens spread globally. Myrtle rust, caused by Austropuccinia psidii, arrived in New Zealand in 2017 and infects at least 12 of 18 species in the susceptible Myrtaceae plant family. Among these are species of structural, successional and cultural importance. We aim to assess whether the functional consequences of Myrtaceae loss could be mitigated if co‐occurring species with shared functional attributes are able to replace them. Location: New Zealand (but with concepts and methodologies that apply globally). Methods: Using a nationwide forest and shrubland plot data set, we assessed community vulnerability to the loss of Myrtaceae species by analysing proportional changes in average trait values when they are absent and produced spatial predictions indicating where species loss might have the greatest impact on community functionality. We then assessed whether compensatory infilling by co‐occurring species would mediate community vulnerability. Results: Forests and shrublands containing Kunzea ericoides and Leptospermum scoparium are highly vulnerable to their loss. Areas most vulnerable overall are the central and south‐eastern North Island, north‐eastern South Island and Stewart Island. For all species, compensatory infilling moderated the impact of their loss. However, if co‐occurring Myrtaceae were unable to respond, possibly if they were also infected, community vulnerability almost always increased because infilling species had different functional attributes, compounding the functional impact. Main Conclusions: Early successional woody plant communities and Myrtaceae‐dominated old‐growth forests are at most risk. Our spatial assessment of species‐level functional impacts from myrtle rust will facilitate better‐informed landscape‐level responses. Management actions and monitoring can now be targeted to areas and communities at greatest risk of losing ecosystem‐level processes. [ABSTRACT FROM AUTHOR]

The ecologically and culturally vital tree species, ʻōhiʻa lehua (Metrosideros polymorpha), is threatened by the fungal pathogens Ceratocystis lukuohia and Ceratocystis huliohia, the causal agents of the disease complex called Rapid ʻŌhiʻa Death (ROD). Four invasive ambrosia beetle (Coleoptera: Curculionidae: Scolytinae) species in the Xyleborini tribe colonize ROD Ceratocystis‐infested 'ōhiʻa and produce inoculum through their frass; however, the potential for direct transmission of the ROD fungi by these beetles was unknown. We fulfilled Leach's rules to support insect transmission of ROD by documenting the visitation of these ambrosia beetles to healthy 'ōhiʻa trees, culturing C. lukuohia and C. huliohia from the ROD‐associated beetles using three different collection methods at multiple study sites, and challenging healthy ʻōhiʻa seedlings with beetles that were exposed to both C. lukuohia and C. huliohia cultures. We documented all four invasive ROD‐associated ambrosia beetle species including Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, and Xyleborus perforans to regularly visit healthy ʻōhiʻa trees on sticky traps. Viable Ceratocystis propagules were isolated from all species, and C. lukuohia was most commonly isolated of the two ROD‐causing fungi. Consistently across all collection techniques, ROD Ceratocystis spp. were detected on just under 3% of all assayed beetles, with the highest detection rate from X. affinis. All four beetle species were capable of directly transmitting both pathogens to healthy ʻōhiʻa seedlings with a high rate of transfer. Ceratocystis spp. are highly virulent pathogens in trees, and a single inoculation can result in tree death, therefore any direct transmission is a cause for concern. After meeting the criteria of Leach's rules, we propose that Xi. saxesenii, X. affinis, X. ferrugineus, and X. perforans are vectors of C. lukuohia and C. huliohia, particularly in areas of high ROD pressure and tree stress. [ABSTRACT FROM AUTHOR]

Premise: The isolation of RNA from trees is challenging due to the interference of polyphenols and polysaccharides with downstream processes. Furthermore, many RNA extraction protocols are time consuming and involve hazardous chemicals. To address these issues, we aimed to develop a safe protocol for high‐quality RNA extraction from diverse Metrosideros taxa representing a broad range of leaf toughness, pubescence, and secondary metabolites. Methods and Results: We tested popular RNA isolation kits and protocols that were effective on other recalcitrant trees, including a broad range of optimization and purification steps. We optimized a protocol involving two silica‐membrane column‐based kits that yielded high‐quantity RNA with an RNA integrity number >7 and without DNA contamination. All RNA samples were used successfully in a follow‐on RNA‐Seq experiment. Conclusions: We present an optimized high‐throughput RNA extraction protocol that yielded high‐quality and high‐quantity RNA from three contrasting leaf phenotypes within a hyperdiverse woody species complex. [ABSTRACT FROM AUTHOR]

The argan tree (Argania Spinosa) grows mainly in Morocco. This forest species, also called iron tree, covers about 830000 ha of Moroccan territory. Virtues of this argan oil are multiple: uses for cooking, medicines, or cosmetics. The objective of this work is the valorization of the argan tree, and especially in its shell, which remains poorly exploited and which is sold by the premises at low prices for use as a fuel in the Moorish baths and bakeries. Argan shell is the reinforcement of this bio-composite. For this, the shell is ground, sieved and separated into five different diameters d. Then, the preparations of the three ranges, each of which is composed of proportions (20%, 60%, 20%) of increasing diameter of particles. Each particle range is used as reinforcement in a matrix of urea formaldehyde and water as a non-polluting solvent. Using a traction machine, the Young module and the breaking stress of the three biomaterial ranges were determined. Our results show that the Young module of first range (R1) remains superior to that of other two ranges and also has a high breaking voltage. Then the bending measurements were made by the three-point machine MTS EM Flexion. Our results show that the R1 has a greater bending stress than the other two ranges. [ABSTRACT FROM AUTHOR]

Aims: The Myrtaceae is a woody family that plays an important role in forest ecosystems globally. The recent spread of myrtle rust, caused by a fungal pathogen (Austropuccinia psidii), from its native South America into New Zealand (NZ), highlights the need to quantify the ecological importance of Myrtaceae in NZ woody ecosystems. Location: New Zealand. Methods: Using NZ nationwide forest and shrubland inventory data, collected from 2009 to 2014, we quantified the ecological importance of Myrtaceae based on its richness and abundance relative to co-occurring woody families. We then explored how climate and forest stand structure affect Myrtaceae importance in general and by tribe and growth form. Finally, we compared functional traits associated with plant growth and reproductive strategies with other dominant woody families and determined Myrtaceae's contributions to community-weighted mean (CWM) trait values. Results: Myrtaceae occurred in 74% of the study plots and its importance value was the second highest across the woody families. It was the only one in which climbers substantially contributed to the importance value (17%). Greater Myrtaceae importance values were associated with warmer and more mesic climates and early forest successional stages. Climate associations were similar within tribes and growth forms, whereas forest structure effects varied. Myrtaceae was functionally distinct from most co-occurring woody families. Contributions to CWM wood density, maximum height, and specific leaf area values were significantly greater than expected from its importance value. Conclusions: Myrtaceae is the second most ecologically important woody family in NZ woody ecosystems. The family has a distinctive functional trait spectrum associated with high wood density and tall stature, ensuring large and enduring carbon stocks. There will potentially be large and deleterious outcomes in forest ecosystems if taxon-specific pathogens, such as Austropuccinia psidii, spread and significantly reduce Myrtaceae importance. [ABSTRACT FROM AUTHOR]

Metrosideros (Myrtaceae) comprises 58 woody species distributed across Oceania and with three singleton outliers in Philippines, South America and Africa. Centres of species richness occur in New Zealand and New Caledonia. This distribution accords with a proposed Gondwanan origin for the family. While the phylogeography of one component of the genus – subgenus Metrosideros – has received some examination, the rest of the genus has not been resolved. In this study, we improve resolution of the phylogeny of Metrosideros and consider origin, possible vicariant relationships, long‐distance dispersal events and dispersal routes for the genus. A Bayesian phylogeny, with all but one recently described species of Metrosideros, was constructed using concatenated ITS + ETS rDNA from samples we collected and sequenced. Relative to previous work on Metrosideros using ITS alone, here, using ITS plus ETS, we produce a more detailed and robust phylogeny with a near threefold increase in significant nodal support. Putative centres of origin/diversification, vicariant events and dispersals were considered with reference to the phylogeny, present‐day diversity and fossil record of Metrosideros. Metrosideros occurs as five clades, including the former genera Tepualia and Carpolepis. The paraphyletic and now superseded subgenus Mearnsia included elements of four of these clades, whereas subgenus Metrosideros forms a single clade with robust support. Our phylogeography indicates multiple dispersal/vicariant events within the history of the genus, a number of which involved New Zealand. Among other such events, we infer an exceptional 6300 km trans‐equatorial dispersal from Fiji to the Bonin Islands (Japan). Australia and New Zealand, respectively, are the likely landmasses of origin and diversification for Metrosideros. Typical patterns of floral dispersal proceed from large continental landmasses onto increasingly remote islands and with distance from continent species diversity usually declines. However, Metrosideros shows a countervailing pattern since relatively remote islands are the main centres of speciation and dispersal. [ABSTRACT FROM AUTHOR]

Some of the most spectacular adaptive radiations begin with founder populations on remote islands. How genetically limited founder populations give rise to the striking phenotypic and ecological diversity characteristic of adaptive radiations is a paradox of evolutionary biology. We conducted an evolutionary genomics analysis of genus Metrosideros, a landscape-dominant, incipient adaptive radiation of woody plants that spans a striking range of phenotypes and environments across the Hawaiian Islands. Using nanopore-sequencing, we created a chromosome-level genome assembly for Metrosideros polymorpha var. incana and analyzed whole-genome sequences of 131 individuals from 11 taxa sampled across the islands. Demographic modeling and population genomics analyses suggested that Hawaiian Metrosideros originated from a single colonization event and subsequently spread across the archipelago following the formation of new islands. The evolutionary history of Hawaiian Metrosideros shows evidence of extensive reticulation associated with significant sharing of ancestral variation between taxa and secondarily with admixture. Taking advantage of the highly contiguous genome assembly, we investigated the genomic architecture underlying the adaptive radiation and discovered that divergent selection drove the formation of differentiation outliers in paired taxa representing early stages of speciation/divergence. Analysis of the evolutionary origins of the outlier single nucleotide polymorphisms (SNPs) showed enrichment for ancestral variations under divergent selection. Our findings suggest that Hawaiian Metrosideros possesses an unexpectedly rich pool of ancestral genetic variation, and the reassortment of these variations has fueled the island adaptive radiation. [ABSTRACT FROM AUTHOR]

Stands of the landscape‐dominant tree, Metrosideros polymorpha ('ōhi'a) on the Island of Hawai'i, HI., USA, are dying from a phenomenon known as rapid 'ōhi'a death (ROD). Approximately 180,000 acres of forest have already been impacted by the disease, the majority of which is attributed to C. lukuohia, the more aggressive of the two Ceratocystis species responsible for ROD. Three isolates of C. lukuohia were compared for differences in aggressiveness. Mean disease severity and mean number of days to death did not differ among the three isolates of C. lukuohia. A single isolate was selected for use in a resistance screening of 128 plants across four varieties of M. polymorpha occurring on Hawai'i Island: incana, glaberrima, polymorpha and newellii. Disease severity was lower in early‐successional var. incana (38.84%) and riparian var. newellii (36.11%) compared to late‐successional var. glaberrima (61.27%) and high‐elevation var. polymorpha (70.27%). Var. incana and var. newellii also had the lowest mortality (63% and 77%, respectively) while var. glaberrima (86%) and var. polymorpha (100%) had the highest mortality. Eighty‐five per cent of the plants that died did so within 49 days post‐inoculation and mean number of days to death was significantly higher for var. glaberrima (46) compared to var. polymorpha (31). The results of this preliminary study suggest that some form of resistance might be present in natural populations of at least one variety of M. polymorpha on Hawai'i Island and should be investigated more intensively. [ABSTRACT FROM AUTHOR]

The global spread of invasive plant pathogens is increasing, putting natural forests and ecosystem services under threat. Spatial data can quantify range non‐overlap between invasive pathogens and their hosts to identify existing and potentially restorable refugia to enable 'escape' from the pathogen.In 2017, myrtle rust Austropuccinia psidii was detected in New Zealand. New Zealand has 27 native woody and liana species in the plant family susceptible to the disease (Myrtaceae), many of which are ecosystem dominants and economically important. Spatial methods were used to compare the current New Zealand distribution of myrtle rust with the modelled distributions of its potential native hosts. To guide management and set priorities for conservation of at‐risk species, areas of potential refugia where a Myrtaceae species is predicted to occur outside the pathogen range were identified under two myrtle rust distribution scenarios.Myrtle rust will thrive in New Zealand's warmer regions. Many native Myrtaceae are distributed within this area, but several species occur extensively outside the core range of the disease. Species distributed in cooler southern regions will be best placed to persist in refugia.Myrtaceae species with specific habitat requirements and narrow geographical ranges in warmer (northern) areas are likely to require ex situ or active in situ management. Even widely distributed species will benefit from the restoration of suitable habitat that supports multiple species outside the myrtle rust range.Synthesis and applications. Spatial data can be used to identify refugia and restoration opportunities, and thus inform landscape‐level management responses to invasive pathogens. This approach can guide decisions over where to implement in situ (e.g. fungicide spraying) versus ex situ (e.g. seed banking, botanic gardens) management efforts. [ABSTRACT FROM AUTHOR]

ABC model, Clianthus, Eucalyptus, flowering, gibberellin, growth habit, heteroblasty, homoblasty, Metrosideros, microRNA, Pachycladon, phase change, Phormium, photoperiod, reproduction, Sophora. [Extracted from the article]

Accurate feature annotation as well as assembly contiguity are important requisites of a modern genome assembly. They allow large-scale comparison of genomes across and within species and identification of polymorphisms, leading evolutionary and functional studies. We report an updated genome resource for Metrosideros polymorpha, the most dominant tree species in the Hawaiian native forests and a unique example of rapid and remarkable ecological diversification of woody species. Ninety-one percent of the bases in the sequence assembly (304 Mb) were organized into 11 pseudomolecules, which would represent the chromosome structure of the species assuming the synteny to a close relative Eucalyptus. Our complementary approach using manual annotation and automated pipelines identified 11.30% of the assembly to be transposable elements, in contrast to 4.1% in previous automated annotation. By increasing transcript and protein sequence data, we predicted 27,620 gene models with high concordance from the supplied evidence. We believe that this assembly, improved for contiguity, and annotation will be valuable for future evolutionary studies of M. polymorpha and closely related species, facilitating the isolation of specific genes and the investigation of genome-wide polymorphisms associated with ecological divergence. [ABSTRACT FROM AUTHOR]

Aim: Little is known about how diversification occurs within long‐lived, highly dispersible and continuously distributed groups. We examined the distribution of genetic variation within the woody genus Metrosideros across the Hawaiian Islands for insights into how diversification occurs within this animal‐pollinated, wind‐dispersed group. Among Hawaiian plants, Metrosideros is unique in its formation of continuous stands within islands that span a remarkable range of environments and comprise numerous predominantly single‐island taxa. Location: Hawaiian Islands. Taxon: Metrosideros. Methods: We performed population genetic analyses of variation at nine nuclear microsatellite loci from 1,486 adults of 23 Metrosideros morphotypes sampled from five main Hawaiian Islands plus additional Pacific Island populations. Results: American Samoa and Tahiti populations clustered most closely with the older islands. Results also revealed isolation by distance across the archipelago, clustering of populations predominantly by island, and evidence of multiple colonizations or back‐colonizations of three islands. The number of genetic clusters peaked on islands of intermediate age, coincident with peak morphotype richness. All islands comprised a broad range of genetic distances among taxa with the greatest overall genetic distance observed on Oahu. The two taxa that are distributed broadly across the archipelago were weakly but significantly differentiated only on volcanically active Hawaii Island, where they partition early‐ and late‐successional environments. One of these taxa was positioned centrally both within individual‐island splitstree networks and across the archipelago‐wide network. Main conclusions: Distance‐dependent gene flow contributes to isolation of Metrosideros across islands, especially on terminal islands. Morphological diversity likely accumulates rapidly within this group, likely associated with differential adaptation across heterogeneous environments, but isolation of gene pools through speciation within continuous Metrosideros stands likely requires persistent disruptive selection where environments are stable for long periods. The generalist, wet‐forest M. polymorpha var. glaberrima may play a central role in the generation of the group's many, largely island‐endemic, taxa. [ABSTRACT FROM AUTHOR]

Variation in leaf micromorphology can aid delimitation of taxonomically difficult groups. The woody genus Metrosideros (Myrtaceae) dominates Hawai'i's native forests and comprises striking, predominantly infraspecific, macromorphological variation, including many forms unrecognized in current taxonomic treatments. On taxonomically rich O'ahu, 10 taxa (varieties or unnamed morphotypes of M. polymorpha and other species) occur in a predictable sequence with overlapping ranges from low to high elevation along the numerous leeward ridges of the Ko'olau Range. We used scanning electron and light microscopy to examine mature, nonsenescing sun leaves from each of these 10 taxa. Parametric and nonparametric tests were used to compare stomatal complex (SC) traits and those of a newly described secretory structure (SS) across taxa. Correlations among traits and discriminant analyses were also done. Density and length of SCs were inversely related overall, and both measures varied significantly across taxa. Although abaxial SSs were consistently present only in the two highest-elevation glabrous taxa, adaxial SSs were present in all 10 taxa. Length and density of adaxial SSs and density of abaxial SSs varied across taxa, and densities of both SCs and SSs were greatest at high elevation. Combined, the SC and SS traits differentiated 100% of four glabrous varieties and two of three pubescent varieties of M. polymorpha. Variation in leaf micromorphology, including presence and density of a newly described SS, aids delimitation of closely related Hawaiian Metrosideros taxa and may reflect differential local adaptation across a heterogeneous landscape. [ABSTRACT FROM AUTHOR]

The native 'ōhi'a lehua (Metrosideros polymorpha) has cultural, biological and ecological significance to Hawai'i, but it is seriously threatened by a disease commonly referred to as rapid 'ōhi'a death (ROD). Preliminary investigations showed that a Ceratocystis species similar to C. fimbriata s.lat. was the cause of the disease. In this study, we used a combination of the phylogenetic, morphological and biological species concepts, as well as pathogenicity tests and microsatellite analyses, to characterise isolates collected from diseased 'ōhi'a trees across Hawai'i Island. Two distinct lineages, representing new species of Ceratocystis, were evident based on multigene phylogenetic analyses. These are described here as C. lukuohia and C. huliohia. Ceratocystis lukuohia forms part of the Latin American clade (LAC) and was most closely associated with isolates from Syngonium and Xanthosoma from the Caribbean and elsewhere, including Hawai'i, and C. platani, which is native to eastern USA. Ceratocystis huliohia resides in the Asian-Australian clade (AAC) and is most closely related to C. uchidae, C. changhui and C. cercfabiensis, which are thought to be native to Asia. Morphology and interfertility tests support the delineation of these two new species and pathogenicity tests show that both species are aggressive pathogens on seedlings of M. polymorpha. Characterisation of isolates using microsatellite markers suggest that both species are clonal and likely represent recently-introduced strains. Intensive research is underway to develop rapid screening protocols for early detection of the pathogens and management strategies in an attempt to prevent the spread of the pathogens to the other islands of Hawai'i, which are currently disease free. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY:: The capsular‐fruited genus Metrosideros (Myrtaceae) is one of the most widely distributed flowering plant genera in the Pacific but is extinct in Australia today. The center of geographic origin for the genus and the reason for and timing of its extinction in Australia remain uncertain. We identify fossil Metrosideros fruits from the newly discovered Golden Fleece fossil flora in the Oligo‐Miocene of Tasmania, Australia, shedding further light on these problems. METHODS:: Standard paleopalynological techniques were used to date the fossil‐bearing sediments. Scanning electron microscopy and an auto‐montage camera system were used to take high‐resolution images of fossil and extant fruits taken from herbarium specimens. Fossils are identified using a nearest‐living‐relative approach. KEY RESULTS:: The fossil‐bearing sediments are palynostratigraphically dated as being Proteacidites tuberculatus Zone Equivalent (ca. 33–16 Ma) in age and provide a confident Oligo‐Miocene age for the macrofossils. Two new fossil species of Metrosideros are described and are here named Metrosideros dawsonii sp. nov. and Metrosideros wrightii sp. nov. CONCLUSIONS:: These newly described fossil species of Metrosideros provide a second record of the genus in the Cenozoic of Australia, placing them in the late Early Oligocene to late Early Miocene. It is now apparent not only that Metrosideros was present in Australia, where the genus is now extinct, but that at least several Metrosideros species were present during the Cenozoic. These fossils further strengthen the case for an Australian origin of the genus. [ABSTRACT FROM AUTHOR]

Abstract: Whereas disruptive selection imposed by heterogeneous environments can lead to the evolution of extrinsic isolating barriers between diverging populations, the evolution of intrinsic postzygotic barriers through divergent selection is less certain. Long‐lived species such as trees may be especially slow to evolve intrinsic isolating barriers. We examined postpollination reproductive isolating barriers below the species boundary, in an ephemeral hybrid zone between two successional varieties of the landscape‐dominant Hawaiian tree, Metrosideros polymorpha, on volcanically active Hawai'i Island. These archipelago‐wide sympatric varieties show the weakest neutral genetic divergence of any taxon pair on Hawai'i Island but significant morphological and ecological differentiation consistent with adaptation to new and old lava flows. Cross‐fertility between varieties was high and included heterosis of F1 hybrids at the seed germination stage, consistent with a substantial genetic load apparent within varieties through low self‐fertility and a lack of self‐pollen discrimination. However, a partial, but significant, barrier was observed in the form of reduced female and male fertility of hybrids, especially backcross hybrids, consistent with the accumulation of genetic incompatibilities between varieties. These results suggest that partial intrinsic postzygotic barriers can arise through disruptive selection acting on large, hybridizing populations of a long‐lived species. [ABSTRACT FROM AUTHOR]

Genomewide markers enable us to study genetic differentiation within a species and the factors underlying it at a much higher resolution than before, which advances our understanding of adaptation in organisms. We investigated genomic divergence in Metrosideros polymorpha, a woody species that occupies a wide range of ecological habitats across the Hawaiian Islands and shows remarkable phenotypic variation. Using 1659 single nucleotide polymorphism ( SNP) markers annotated with the genome assembly, we examined the population genetic structure and demographic history of nine populations across five elevations and two ages of substrates on Mauna Loa, the island of Hawaii. The nine populations were differentiated into two genetic clusters distributed on the lower and higher elevations and were largely admixed on the middle elevation. Demographic modelling revealed that the two genetic clusters have been maintained in the face of gene flow, and the effective population size of the high-altitude cluster was much smaller. A FST-based outlier search among the 1659 SNPs revealed that 34 SNPs (2.05%) were likely to be under divergent selection and the allele frequencies of 21 of them were associated with environmental changes along elevations, such as temperature and precipitation. This study shows a genomic mosaic of M. polymorpha, in which contrasting divergence patterns were found. While most genomic polymorphisms were shared among populations, a small fraction of the genome was significantly differentiated between populations in diverse environments and could be responsible for the dramatic adaptation to a wide range of environments. [ABSTRACT FROM AUTHOR]

Fifty male and fifty female Spargue-Dawley rats were randomly chosen and used to study the sexual dimorphisms of stomachic histological structures. The rat stomach consisted of the nonglandular part and the glandular part. The gender differences of the nonglandular part existed in the thicknesses of the stratified squamous epithelium and the longitudinal muscle. These findings revealed that the male rat stomach may storage more foods than the female. The gastric glands occupied all the lamina propria in the glandular part. The thicknesses of the gastric glands of the female and male rat were 525.0 ± 95.9 mm and 472.0 ± 158.7 mm respectively, and the difference was very significant (p<0.01). The gastric glands could be divided to two layers in the HE stain, i.e. the luminal and the basal layers. The thicknesses of the luminal layer of the female and male rat were 289.7 ± 95.9 mm and 300.0 ± 120.7 mm respectively, and the difference was insignificant (p>0.05). On the contrary, the thicknesses of the basal layer and the three muscle layers in the female glandular part were all thicker than those in male, and the differences were very significant (P<0.01). These findings indicated that the female rat stomachs may have a more powerful digestive ability than the male ones. The nucleus-glandular index of the gastric gland of the normal female and male rat were 0.19 ± 0.05 and 0.18 ± 0.04 respectively, and the difference was insignificant (p>0.05). [ABSTRACT FROM AUTHOR]

The histology and histochemistry of the adrenal gland of the African giant rat, AGR (Cricetomys gambianus Waterhouse) was carried out using ten adult male rats with the knowledge of providing information which could be helpful in an improved knowledge of the structure and function of the gland. The adrenal gland of the African giant rat has a distinct cortex and medulla surrounded by a thin rim of capsule. The adrenal cortex has three zones which are basically the zona glomerulosa, zona fasiculata and zona reticularis with the absence of zona intermedia. The zona glomerulosa contains polyhedral cells which form irregular clusters or cords while the zona fasiculata had radial cells of cuboidal or polyhedral shape. The cells of zona reticularis are similar to those of the zona fasiculata and in addition contain small cells as irregular cords and clusters. The cells of the adrenal medulla are composed of irregular epithelioid cells arranged in rounded groups or short cords and are mostly columnar or polyhedral chromaffin cells which are separated by sinusoids. The adrenal capsule, cortex and medulla were Periodic Acid-Schiff-positive.The adrenal capsule and adrenal medulla was Masson Trichrome-positive unlike the zona fasiculata and zona reticularis. The adrenal capsule and zona glomerulosa were Verhoeff-positive unlike the other zones of the gland. In conclusion the histology of the adrenal gland of the AGR is similar to those of other mammals with a few exceptions, the entire gland is rich in carbohydrate while the capsule and by extension, the outermost portion of the cortex are rich in collagen and elastic fibers. The outcome of this research provides information needed in the better improved understanding of the structure and function of the adrenal gland of the animal. [ABSTRACT FROM AUTHOR]

Foliar architecture of Myrtaceae native species of the Argentinian flora IV. Tribes Myrteae and Metrosidereae and key based on foliar characters. This work completes the leaf architecture of native species of Myrtaceae from Argentina. In this contribution are studied two native genus of the tribe Myrteae with uncertain position in the past, and the only one native genus of tribe Metrosidereae in South America. One species of Blepharocalyx and two species of Eugenia are simple, with variable apex and base, leathery texture and entire margin. First vein pinnate, simple and straight, without agrophic veins, second veins broquidodromous, with or without paramarginal and intramarginal veins, third and fourth veins random reticulate or percurrent, and fifth vein random reticulate, percurrent or dichotomized. With or without areoles, with venules branching one, two or more times. The last marginal venation can be complete or incomplete. The leaves of genus Metrosideros are characterized by simple, with acute apex and cuneate base, leathery texture and entire margin. First vein category suprabasal-acrodromous, with agrophic veins, second vein cladodromous or branched, without paramarginal veins and intramarginal veins, and third vein dichotomized. Not develop areoles. Venules branched two or more times. The last marginal venation can be incomplete. Finally, is presented a key to differentiate all native Argentinian species of Myrtaceae, based on characters or character combinations of foliar architecture. [ABSTRACT FROM AUTHOR]

Whole genome sequences, which can be provided even for non-model organisms owing to high-throughput sequencers, are valuable in enhancing the understanding of adaptive evolution. Metrosideros polymorpha, a tree species endemic to the Hawaiian Islands, occupies a wide range of ecological habitats and shows remarkable polymorphism in phenotypes among/within populations. The biological functions of genetic variations observed within this species could provide significant insights into the adaptive radiation found in a single species. Here de novo assembled genome sequences of M. polymorpha are presented to reveal basic genomic parameters about this species and to develop our knowledge of ecological divergences. The assembly yielded 304-Mbp genome sequences, half of which were covered by 19 scaffolds with >5 Mbp, and contained 30 K protein-coding genes. Demographic history inferred from the genome-wide heterozygosity indicated that this species experienced a dramatic rise and fall in the effective population size, possibly owing to past geographic or climatic changes in the Hawaiian Islands. This M. polymorpha genome assembly represents a high-quality genome resource useful for future functional analyses of both intra- and interspecies genetic variations or comparative genomics. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY: Myrtaceous fossil capsular fruits and flowers from the northwest of Tasmania, in the Early Oligocene-aged Little Rapid River (LRR) deposit, are described. The reproductive organs are found in association with Myrtaceous leaves previously thought to belong to a fleshy-fruited genus, Xanthomyrtus at both LRR, and an Eocene Tasmanian site at Hasties, which are reassessed with fresh morphological evidence. METHODS: Standard Light Microscopy (LM) and Scanning Electron Microscopy (SEM) were used to investigate cuticular characters and an auto-montage camera system was used to take high-resolution images of fossil and extant fruits. Fossils are identified using a nearest living relative (NLR) approach. KEY RESULTS: The fossil fruits and flowers share a number of characters with genera of capsular-fruited Myrtaceae, in particular sharing several synapomor-phies with species of Metrosideros subg. Metrosideros (tribe: Metrosidereae). The fossil is here described, and named Metrosideros leunigii, sp. nov. CONCLUSIONS: This research establishes the presence of Metrosideros (aff. subg. Metrosideros) in the Eocene-Oligocene (~40-30 mya) of Tasmania, Australia. This is the first fossil record of Metrosideros in Australia, as well as the oldest conclusive fossil record, and may provide evidence for an Australian origin of the genus. It is also yet another example of extinction in the Tertiary of a group of plants on the Australian mainland that is only found today on nearby Pacific landmasses. [ABSTRACT FROM AUTHOR]

The genus Metrosideros (Myrtaceae) comprises 50-60 species found largely across the Pacific Islands. The relationships within this genus, including the circumscriptions of the subgenera Mearnsia and Metrosideros and their relationships with the other members of the tribe Metrosidereae (namely the New Caledonian endemic genus Carpolepis and the South American Tepualia), are poorly understood. Phylogenetic analyses were carried out using previously published ITS sequences, covering most species of the tribe, and new sequences of five single-copy nuclear genes with a reduced taxon sampling. The independent and combined analyses of the five nuclear genes using a range of approaches, including Bayesian single-gene, concatenated (MrBayes), concordance (BUCKy) and coalescent (*BEAST) analyses, yielded different topologies, indicating important conflicts among phylogenies based on individual genes. The deep relationships within the tribe Metrosidereae remain poorly resolved, but our results indicate that the species of Carpolepis and Tepualia are likely nested in the genus Metrosideros. A broad circumscription of the genus Metrosideros is therefore adopted, and the new combinations Metrosideros laurifolia var. demonstrans, Metrosideros tardiflora and Metrosideros vitiensis are here published. [ABSTRACT FROM AUTHOR]

We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla on intermediate-aged flows (thousands of years). The oldest substrates (tens of thousands of years) were dominated by the short-stature native shrub Dodonaea viscosa and endemic grass Eragrostis atropioides. We excavated 18 macroscopic charcoal fragments from Pleistocene-aged substrates. Mean radiocarbon age was 2,002 years and ranged from < 200 to 7,730. Genus identities from four fragments indicate that Osteomeles spp. or M. polymorpha once occupied the Pleistocene-aged substrates, but neither of these species is found there today. These findings indicate the existence of fires before humans are known to have occupied the Hawaiian archipelago, and demonstrate that a collapse in vertical stature is prevalent on the oldest substrates. This work contributes to our understanding of prehistoric fires in shaping the trajectory of primary succession in Hawaiian drylands. [ABSTRACT FROM AUTHOR]

Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of 'nurse plants' an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native ( Dodonaea viscosa, Leptocophylla tameiameia) and one non-native ( Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability. [ABSTRACT FROM AUTHOR]

Changes in vegetation structure and composition between 1968 and 2013 were assessed on a small rock stack adjoining Slipper Island/Whakahau, located off the east coast of the Coromandel Peninsula. The rock stack, an example of what is an historically rare New Zealand ecosystem, consists of a steep-sided column of fissured andesite with a gently sloped crowning summit (c. 80 m2) that reaches c. 20 m asl. Significant vegetation change occurred in the 45 years between visits, including the arrival of new species (14), predominantly exotic herbs and grasses (7), but most significantly the pioneering native treesMetrosideros excelsaandPittosporum crassifolium. Total vegetation cover frequency on the summit had increased (from 63% to 77%), with a shift from dominance of herbs and grasses to shrubs with incipient forest development. The rock lilyArthropodium bifurcatum(recognised as a distinct form ofArthropodium cirratumin the 1968 survey) had been lost and the light-demanding creeping shrubPimelea urvilleanaconfined to seaward facing ledges. Dominance byM.excelsais expected to increase leading to canopy closure and further compositional changes. [ABSTRACT FROM AUTHOR]

Although trees comprise a primary component of terrestrial species richness, the drivers and temporal scale of divergence in trees remain poorly understood. We examined the landscape-dominant tree, Metrosideros polymorpha, for variation at nine microsatellite loci across 23 populations on young Hawai'i Island, sampling each of the island's five varieties throughout its full geographic range. For four varieties, principal coordinate analysis revealed strong clustering of populations by variety across the 10 430 km2 island, indicating partitioning of the species into multiple evolutionarily significant units. The single island-endemic form, riparian var. newellii, showed especially strong differentiation from other varieties despite occurring in sympatry with other varieties and likely evolved from a bog form on the oldest volcano, Kohala, within the past 500 000 years. Along with comparable riparian forms on other Pacific Islands, var. newellii appears to represent parallel incipient ecological speciation within Metrosideros. Greater genetic distance among the more common varieties on the oldest volcano and an inverse relationship between allelic diversity and substrate age appear consistent with colonization of Hawai'i Island by older, partially diverged varieties followed by increased hybridization among varieties on younger volcanoes. This study demonstrates that broad population-level sampling is required to uncover patterns of diversification within a ubiquitous and long-lived tree species. Hawaiian Metrosideros appears to be a case of incipient radiation in trees and thus should be useful for studies of divergence and the evolution of reproductive isolating barriers at the early stages of speciation. [ABSTRACT FROM AUTHOR]

Nicotine is the most important alkaloid compound in tobacco. One of the major effects of nicotine is stimulation of mesocorticolimbic system. Prefrontal cortex plays a pivotal role in personality and mental state. It is considered the main cause of addiction as it is located in mesocorticolimbic dopamine system. Twenty four male rats were divided into four groups based on nicotine administration dose (0, 0.5, 1 and 1.5 g/kg). After animals were anesthetized, their brains were fixed using transcardiac method. Tissue processing and Golgi staining were performed and the stained tissue sections were analyzed by optic microscope and Motic software. By increasing the dose, nicotine significantly decreased the number of neuronal processes. In the higher dose, nicotine caused a significant decrease and increase in the size of pericarions and dendritic spines, respectively (p<0.05). Nicotine administration can decrease the size of pericarion and number of dendritic spines in the prefrontal cortex. [ABSTRACT FROM AUTHOR]

ABSTRACT An improved fish smoking kiln was designed and fabricated. Catfish samples were smoked using three biomasses, namely iron tree, sawdust and rice husk. Variations in utilizable temperatures with time, phenol contents, smoke density, weight loss, proximate composition and sensory qualities of the smoked fish were evaluated. The utilizable temperatures due to combustion of constant weight of each biomass ranged from 60 to 120C for sawdust, 61.5 to 132C for rice husk and 60 to 120C for iron tree in 5 h. The temperatures due to combustion of iron tree, rice husk and sawdust decline to a constant value. The temperature of iron tree showed steadier decline. The phenol content ranged from 0.42 to 0.48 mg/mL with rice husk having the highest value while iron tree had the lowest value. Smoke density ranged from 0.021 to 0.024 g/cm3 showing the same trend. Proximate analysis shows significant difference ( P < 0.05) in moisture, protein, lipids and ash. However, carbohydrate content does not change significantly ( P > 0.05). Organoleptically, catfish smoked with iron tree yielded the best quality and was significantly ( P < 0.05) superior to that smoked with sawdust and rice husk. Samples smoked with sawdust were least preferred. PRACTICAL APPLICATIONS The oven would be used for drying of fish which will lead to the reduction of postharvest fish losses. [ABSTRACT FROM AUTHOR]

The genus Metrosideros includes several tree, shrub and vine species, native to the Pacific Islands. Seedlings from 25 seed lots of Metrosideros polymorpha and two seed lots of M. tremuloides with symptoms of root rot, stem girdling, wilting and round, purple leaf spots were observed in the Forestry Nursery at the Universidade Federal de Viçosa, Brazil. In the original disease site, seedling mortality reached up to 71% in M. polymorpha and 34% in M. tremuloides. Single conidial cultures obtained from infected leaf, root and stem samples of M. polymorpha were used to identify the fungal species. Morphological characters and DNA sequences of four loci, containing partial sequences of β-tubulin ( TUB2), histone H3 ( HIS3), calmodulin ( CAL) and the elongation factor ( tef-1α) genes of three isolates, indicated that they belong to a new species, described here as Calonectria metrosideri sp. nov. Potting medium infestation and inoculation of seedlings of M. polymorpha with an inoculum suspension at 1 × 104 conidia ml−1 induced typical symptoms of the disease (leaf spots, root rot and wilt), similar to those observed under natural conditions. Calonectria metrosideri was re-isolated, which fulfilled Koch's postulates, and confirmed its status as a pathogen. [ABSTRACT FROM AUTHOR]

Abstract: The Cryphonectriaceae includes important tree pathogens, especially on the Myrtales. During a routine disease survey in the Western Cape Province of South Africa, a fungus resembling the Eucalyptus pathogen Holocryphia eucalypti was observed on native Metrosideros angustifolia (Myrtales). The aims of this study were to identify the fungus and to expand surveys for fungi in the Cryphonectriaceae on M. angustifolia. Fungi were identified based on DNA sequence comparisons and morphological features, and their pathogenicity was tested on M. angustifolia under field conditions. Based on morphology and multigene phylogenetic analyses of DNA sequence data from six gene regions, we describe a new genus including a single species and three new species of Holocryphia (Cryphonectriaceae) from M. angustifolia. These fungi are provided with the names Diversimorbus metrosiderotis gen. et sp. nov., Holocryphia capensis sp. nov., Holocryphia gleniana sp. nov., and Holocryphia mzansi sp. nov. We also revise H. eucalypti, the type of the genus, to include only isolates from Eucalyptus in South Africa. Research results indicated that H. mzansi may undergo host shifts between different tree genera in the Myrtaceae. Inoculation tests showed that isolates of all the newly described species can cause lesions on the branches of M. angustifolia, indicating that they are all pathogens of this tree. [Copyright &y& Elsevier]

On Lord Howe Island, speciation is thought to have taken place in situ in a diverse array of distantly related plant taxa ( Metrosideros, Howea and Coprosma; Proc. Natl Acad. Sci. USA 108, 2011, 13188). We now investigate whether the speciation processes were driven by divergent natural selection in each genus by examining the extent of ecological and genetic divergence. We present new and extensive, ecological and genetic data for all three genera. Consistent with ecologically driven speciation, outlier loci were detected using genome scan methods. This mechanism is supported by individual-based analyses of genotype-environment correlations within species, demonstrating that local adaptation is currently widespread on the island. Genetic analyses show that prezygotic isolating barriers within species are currently insufficiently strong to allow further population differentiation. Interspecific hybridization was found in both Howea and Coprosma, and species distribution modelling indicates that competitive exclusion may result in selection against admixed individuals. Colonization of new niches, partly fuelled by the rapid generation of new adaptive genotypes via hybridization, appears to have resulted in the adaptive radiation in Coprosma - supporting the 'Syngameon hypothesis'. [ABSTRACT FROM AUTHOR]

The management and removal of invasive species may give rise to unanticipated changes in plant-pollinator mutualisms because they can alter the composition and functioning of plant-pollinator interactions in a variety of ways. To utilize a functional approach for invasive species management, we examined the restoration of plant-pollinator mutualisms following the large-scale removal of an invasive nectar thief and arthropod predator, Vespula pensylvanica., We reduced V. pensylvanica populations in large plots managed over multiple years to examine the response of plant-pollinator mutualisms and the fruit production of a functionally important endemic Hawaiian tree species, Metrosideros polymorpha. To integrate knowledge of the invader's behaviour and the plant's mating system, we determined the efficacy of V. pensylvanica as a pollinator of M. polymorpha and quantified the dependence of M. polymorpha on animal pollination (e.g. level of self-compatibility and pollen limitation)., The reduction of V. pensylvanica in managed sites, when compared to unmanaged sites, resulted in a significant increase in the visitation rates of effective bee pollinators (e.g. introduced Apis mellifera and native Hylaeus spp.) and in the fruit production of M. polymorpha., Apis mellifera, following the management of V. pensylvanica, appears to be acting as a substitute pollinator for M. polymorpha, replacing extinct or threatened bird and bee species in our study system., Synthesis and applications. Fruit production of the native M. polymorpha was increased after management of the invasive pollinator predator V. pensylvanica; however, the main pollinators were no longer native but introduced. This research thus demonstrates the diverse impacts of introduced species on ecological function and the ambiguous role they play in restoration. We recommend incorporating ecological function and context into invasive species management as this approach may enable conservation managers to simultaneously minimize the negative and maximize the positive impacts (e.g. taxon substitution) of introduced species. Such novel restoration approaches are needed, especially in highly degraded ecosystems. [ABSTRACT FROM AUTHOR]

Understanding the processes underlying the origin of species is a fundamental goal of biology. It is widely accepted that speciation requires an interruption of gene flow between populations: ongoing gene exchange is considered a major hindrance to population divergence and, ultimately, to the evolution of new species. Where a geographic barrier to reproductive isolation is lacking, a biological mechanism for speciation is required to counterbalance the homogenizing effect of gene flow. Speciation with initially strong gene flow is thought to be extremely rare, and few convincing empirical examples have been published. However, using phylogenetic, karyological, and ecological data for the flora of a minute oceanic island (Lord Howe Island, LHI), we demonstrate that speciation with gene flow may, in fact, be frequent in some instances and could account for one in five of the endemic plant species of LHI. We present 11 potential instances of species divergence with gene flow, including an in situ radiation of five species of Coprosma (Rubiaceae, the coffee family). These results, together with the speciation of Howea palms on LHI, challenge current views on the origin of species diversity. [ABSTRACT FROM AUTHOR]

Abstract: Many tropical island forest ecosystems are dominated by non-native plant species and lack native species regeneration in the understorey. Comparison of replicated control and removal plots offers an opportunity to examine not only invasive species impacts but also the restoration potential of native species. In lowland Hawaiian wet forests little is known about native species seed dynamics, recruitment requirements, or the effects of management. In a heavily invaded lowland wet forest, we examined the relationship between seed presence and seedling establishment in control and removal plots. Non-native species were competitively superior because they had higher germination percentages and dominated the seed bank; only seven out of 33,375 seedlings were native. In contrast, the seed rain contained native seed, but native seedling recruitment was almost exclusively limited to removal plots, suggesting that optimum establishment conditions are not met in the presence of a dense mid-storey of non-native species. Non-native species dominance was altered and biomass significantly decreased over time resulting in a reduced weeding effort (12.38–0.77gday−1). We suggest that with opening of the canopy through non-native species removal and subsequent weeding, it may be possible to reduce the seed bank enough to skew the regeneration potential towards native species. Our results suggest that germination success and lack of a seed bank are the main bottlenecks for native species. We conclude that without invasive species control, future regeneration of Hawaiian lowland wet forests is likely to be almost entirely non-native. [Copyright &y& Elsevier]

Two sediment sequences from Pukekawa crater, Auckland Domain, contain silty clay underlain by fibrous peat. The peat contains a pollen flora and wood indicating the presence of a warm-temperate, conifer-hardwood forest with Metrosideros, Agathis, Prumnopitys taxifolia, P. ferruginea, and especially Dacrydium. Radiocarbon dates indicate that the peat was deposited before the Last Glacial Maximum (LGM). Absence of tephras and small amounts of Fuscospora pollen indicate probable non-preservation of the LGM. The pollen flora of most of the clay contains Metrosideros, Ascarina, and ferns, indicating post-LGM warmer, wetter conditions. The two uppermost samples contain exotic pollen, indicating that they are post-European in origin. Excavation and levelling to form sports fields and parkland appears to have curtailed and mixed the Holocene record. [ABSTRACT FROM AUTHOR]

The range of microhabitats and microclimatic conditions provided by epiphytes has been linked to the high diversity of invertebrates in many forest canopies worldwide, but comparably little is known about the invertebrate fauna in this habitat in New Zealand. This study compiled an inventory of the invertebrate fauna of epiphyte mats in the canopy of northern rata (Myrtaceae: Metrosideros robusta A. Cunn.) at two study sites on the West Coast of the South Island. A total of 242 069 invertebrate specimens was collected over one year, representing 4 phyla, 9 classes and more than 160 families, 225 genera and 446 species. At least 10 new species and 3 new genera were identified, while 5 species were recorded outside their known geographical range. Epiphyte mats provided habitat for an invertebrate fauna, highly diverse and abundant both taxonomically and functionally, dominated in terms of abundance by Acari, Collembola and hymenoptera (largely ants), and in terms of feeding guilds by epiphyte grazers and ants. As the first inventory of this taxonomic depth and breadth compiled for New Zealand forest epiphyte habitats, this study provides important baseline data for the conservation of biodiversity in New Zealand's indigenous forests. [ABSTRACT FROM AUTHOR]

Aim Non-vascular epiphytes have been largely ignored in studies examining the biotic and abiotic determinants of spatial variation in epiphyte diversity. Our aim was to test whether the spatial patterning of species richness, biomass and community composition across geographic regions, among trees within regions, and among branches within trees is consistent between the vascular and non-vascular components of the temperate rain forest flora. Location Coastal lowland podocarp-broadleaved forests on the west coast of the South Island of New Zealand. Methods We collected single samples (30 × 25 cm) from 96 epiphyte assemblages located on the inner branches of 40 northern rata ( Metrosideros robusta) trees. For each sample, branch characteristics such as branch height, branch diameter, branch angle, branch aspect, and minimum and maximum epiphyte mat depth were recorded. The biomass for each individual epiphyte species was determined. Results Northern rata was host to a total of 157 species, comprising 32 vascular and 125 non-vascular species, with liverworts representing 41% of all species. Within epiphyte mats, the average total organic biomass of 3.5 kg m−2 of branch surface area consisted largely of non-living biomass and roots. Vascular and non-vascular epiphytes showed strikingly different spatial patterns in species richness, biomass and composition between sites, among trees within sites, and among branches within trees, which could not be explained by the branch structural characteristics we measured. The two plant groups had no significant association in community composition ( r = 0.04, P = 0.08). However, the species richness of vascular plant seedlings was strongly linked to the presence/absence of lichens. Main conclusions Non-vascular plants contributed substantially to the high species richness and biomass recorded in this study, which was comparable to that of some tropical rain forests. High variability in community composition among epiphyte mats, and very low correlation with any of the environmental factors measured possibly indicate high levels of stochasticity in seed or spore colonization, establishment success or community assembly among branches in these canopy communities. Although we found some evidence that vascular plant seedling establishment was linked to the presence of lichens and the biomass of non-living components in the epiphyte mats, there was no correlation in the spatial patterning or determinants of species richness between non-vascular and vascular plants. Consequently, variation in total epiphyte biodiversity could not be predicted from the measurement of vascular plant diversity alone, which highlights the crucial importance of sampling non-vascular plants when undertaking epiphyte community studies. [ABSTRACT FROM AUTHOR]

Conservation of endemic species on oceanic islands is an essential issue for biodiversity conservation. Metrosideros boninensis (Myrtaceae) is an endangered tree species endemic to the Bonin Islands of the western North Pacific Ocean. This species is considered to be extremely rare with less than 400 adult individuals, a number that has fluctuated between the 1880s and 1980s through human influence. We analyzed the genetic diversity and genetic structure of this species using amplified fragment length polymorphism markers and microsatellite markers. Genetic diversity of M. boninensis was extremely low compared to related taxa and similar endemic species from small islands. This low genetic diversity might be attributed to a stepwise colonization process with repeated founder bottlenecks in the dispersal pathway to the Bonin Islands. Populations of M. boninensis showed significant genetic differentiation and isolation by distance over a small geographical scale, despite the fact that this species should have extensive gene dispersal ability. This genetic differentiation might be caused by limited gene flow via pollen and seed among populations and genetic drift amid a small number of remnant individuals. Taken together, these findings suggest that the genetic diversity and connectivity of tree populations on islands are more vulnerable to habitat fragmentation than previously thought. We offer some recommendations for management to ameliorate habitat fragmentation and biological invasion. [ABSTRACT FROM AUTHOR]

Knowledge of the evolutionary history of plants that are ecologically dominant in modern ecosystems is critical to understanding the historical development of those ecosystems. Metrosideros is a plant genus found in many ecological and altitudinal zones throughout the Pacific. In the Hawaiian Islands, Metrosideros polymorpha is an ecologically dominant species and is also highly polymorphic in both growth form and ecology. Using 10 non-coding chloroplast regions, we investigated haplotype diversity in the five currently recognized Hawaiian Metrosideros species and an established out-group, Metrosideros collina, from French Polynesia. Multiple haplotype groups were found, but these did not match morphological delimitations. Alternative morphologies sharing the same haplotype, as well as similar morphologies occurring within several distinct island clades, could be the result of developmental plasticity, parallel evolution or chloroplast capture. The geographical structure of the data is consistent with a pattern of age progressive island colonizations and suggests de novo intra-island diversification. If single colonization events resulted in a similar array of morphologies on each island, this would represent parallel radiations within a single, highly polymorphic species. However, we were unable to resolve whether the pattern is instead explained by ancient introgression and incomplete lineage sorting resulting in repeated chloroplast capture. Using several calibration methods, we estimate the colonization of the Hawaiian Islands to be potentially as old as 3.9 (−6.3)Myr with an ancestral position for Kaua'i in the colonization and evolution of Metrosideros in the Hawaiian Islands. This would represent a more ancient arrival of Metrosideros to this region than previous studies have suggested. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that trees growing at high elevations with occasional freezing temperatures have smaller diameter xylem vessels than trees of the same species growing at lower and warmer elevations. The young branch wood of the wide-ranging Hawaiian tree species Metrosideros polymorpha (Myrtaceae) was examined in three natural field populations (high, middle, and low elevations: 2469, 1280, and 107 m a.s.l., respectively) and contrasted with seedlings from these populations that were grown in a common garden at middle elevation (1190 m). Previous studies showed that these populations have some genetic differences and have distinctive leaf structure and ecophysiological traits. Vessel diameter was significantly smaller in the high elevation field and common garden plants than in middle elevation plants. However, high elevation vessels were wider in common garden plants compared to field plants, indicating that vessel diameter is determined both by genotype (parental populations) and environment (growing conditions different from those of parents). Reduced vessel diameter has implications for resistance to cavitation induced by freezing and/or drought in plants growing near tree line in Hawaii. [ABSTRACT FROM AUTHOR]

We compiled a time series of Earth Observing-1 Hyperion satellite observations with field measurements to compare the structural, biochemical, and physiological characteristics of an invasive nitrogen-fixing tree Myrica faya and native Metrosideros polymorpha in montane rainforests in Hawai’i. Satellite-based canopy water measurements closely tracked variations in leaf area index, and the remotely sensed photochemical and carotenoid reflectance indices (PRI, CRI) indicated variations in upper-canopy leaf chlorophyll and carotenoid content during a climatological transition. The PRI and CRI were related to differences in light-use efficiency of each species, as indicated by field measurements of leaf electron transport rate. The suite of hyperspectral metrics indicated maximum differences in the structure, biochemistry, and physiology of Myrica and Metrosideros when canopy vapor pressure deficit was high during hotter and drier periods. These satellite data, combined with the Carnegue-Ames-Stanford Approach (CASA) carbon cycle model, suggested that Myrica growth rates were 16–44% higher than Metrosideros, with relative differences between species closely linked to climate conditions. The satellite hyperspectral data identified the basic biological mechanisms favoring the spread of an introduced tree, and provided a more detailed understanding of how vegetation–climate interactions affect the time course of plant growth with respect to the invasion process. [ABSTRACT FROM AUTHOR]

Leaves often decline in nutritional quality as they age, and selective feeding on young leaves may be nutritionally important for herbivores. Preference by mammalian herbivores for young leaves has rarely been measured in the field owing to technical difficulties. We measured preferences with respect to leaf age of an arboreal folivore, the brushtail possum ( Trichosurus vulpecula Kerr), feeding on southern rata ( Metrosideros umbellata Cav.; Myrtaceae) in a new application of the alkane technique. We characterized the cuticle waxes (n-alkanes) of rata leaves that were less than 1 year old (‘1-year’), between 1 and 2 years (‘2-year’) and greater than 2 years old (‘>2-year’). Simulations showed that the method accurately discriminated between 1-year and other age groups but slightly overestimated the importance of rare components of the diet. This bias was larger when discriminating between 2-year and >2-year leaves apparently because they had more-similar alkane profiles. Metrosideros umbellata leaf formed 20.8% of the diet of a population of possums from Rakiura, New Zealand, sampled in autumn 2002 ( n = 33). Of the M. umbellata component, alkane analyses showed that 1-year leaves formed 88.7 ± 3.9% of the diet despite making up only 39.5 ± 2.2% of the leaf biomass on rata trees ( n = 14). The foliar concentrations of the macronutrients N, P and K all declined significantly with leaf age ( P < 0.0001). Lignin content did not measurably increase with leaf age, suggesting that digestibility per se did not determine the preference of brushtail possums for young rata leaves. This study provides the first quantitative evidence that possums discriminate by leaf age and that the resulting diet is enriched in macronutrients. [ABSTRACT FROM AUTHOR]

Nine species of rust fungi (Uredinales) were found during a 1-day field study in an Acacia koa–Metrosideros polymorpha woodland in Volcanoes National Park on Big Island, Hawaii. Two species, both found on Acacia koa, are native (endemic) rusts whereas 7 species are nonnative on nonnative hosts, highlighting the high proportion of introduced species in the Hawaiian flora even in more or less natural habitats. One species, Uromyces linearis on Panicum repens, constitutes the first record of this rust for the Hawaiian archipelago, bringing the total to 93 species on the islands, 70 (75.3%) of which are introduced. The species records are annotated with emphasis on the geographic origin of each taxon. In addition, the study has led to the molecular reevaluation of the genus Racospermyces, indicating that it is synonymous with Endoraecium, and six new combinations are proposed for the species previously placed in Racospermyces. The high number of introduced species in Hawaii coupled with the paucity of native species when compared to other global regions is discussed. [ABSTRACT FROM AUTHOR]

Light interception by coal and overburden dusts and flyash with median particle diameters of 120, 70 and 120μm, respectively, were examined at dust loads up to 20g m-2 in an experimental arrangement. The light extinction coefficients (K) of the coal, overburden and flyash dusts were 0.032, 0.016 and 0.0056, respectively. There was an inverse logarithmic relationship between K and median particle diameter that was consistent for the present experimental data and for mineral dust particles with median diameters between 0.14 and 120μm. The temperatures of leaves of Eucalyptus tereticornis (waxy surface), Harpullia pendula (shiny surface) and Metrosideros tomentosa (hairy surface) were examined under conditions of uniform radiation and differing loads of the three dusts. Flyash caused a detectable increase in temperature only in Metrosideros when 10g m-2 was applied to the leaf. Overburden dust resulted in significant increases in leaf temperature of all species at both 5 and 10g m-2, and coal dust applied at 10g m-2 resulted in leaf temperature increase of about 5°C in Harpullia and Metrosideros. The increase in leaf temperature for each type of mineral dust could be described in terms of the incident shortwave radiation and dust load. [ABSTRACT FROM AUTHOR]

Abstract: Five unusual C-methylflavonoids lacking B-ring oxygenation (2′,4′-dihydroxy-3′,5′-dimethyl-6′-methoxychalcone, 2′,4′-dihydroxy-3′-methyl-6′-methoxychalcone, 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone, 2′-hydroxy-3′-methyl-4′,6′-dimethoxychalcone and 5,7-dihydroxy-6,8-dimethylflavanone) were found for the first time in Metrosideros excelsa. The flavanone was the major constituent in leaves, whereas 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone dominated all other aerial plant parts studied. Other Metrosideros species were investigated for these five flavonoids. C19–C36 aldehydes and C22–C32 alcohols were also identified from the dried seed capsules of M. excelsa. [Copyright &y& Elsevier]

We measured the plasticity of the response of photosynthesis to nutrient supply in seedlings of the dominant four conifer and broadleaved angiosperm tree species from an indigenous forest in South-westland, New Zealand. We hypothesized that the response of conifers to differing nutrient supply would be less than the response for the angiosperms because of greater adaptation to low fertility conditions. In Prumnopitys ferruginea (D. Don) de Laub. the maximum velocity of electron transport, Jmax, doubled with a 10-fold increase in concentration of nitrogen supply. In Dacrydium cupressinum Lamb. the maximum velocity of carboxylation, Vcmax, doubled with a 10-fold increase in phosphorus supply. In contrast, photosynthetic capacity for the angiosperm species Weinmannia racemosa L.f. was affected only by the interaction of nitrogen and phosphorus and photosynthetic capacity of Metrosideros umbellata Cav. was not affected by nutrient supply. The response of the conifers to increasing availability of nutrient suggests greater plasticity in photosynthetic capacity, a characteristic not generally associated with adaptation to soil infertility, thus invalidating our hypothesis. Our data suggest that photosynthetic response to nutrient supply cannot be broadly generalized between the two functional groups. [ABSTRACT FROM AUTHOR]

Because of its remoteness and mid-latitude position, New Zealand lacks access to the tropical climates that might have ensured straightforward survival for frost-sensitive species during glacial times. Nevertheless, the New Zealand lowland flora retains a substantial complement of plants sourced in the tropics. While there have been extinction pulses for elements of the frost-sensitive flora under glacial/stadial regimes, the surviving remnants have been able to recolonize large areas of habitat during successive warm climate periods. Refugia for such species in stadial New Zealand are likely to have been localized and ecologically suboptimal. To examine these relationships we have applied chloroplast DNA sequence data to the investigation of phylogeographical pattern for five endemic species ofMetrosiderossubg.Metrosideros, a wide-ranging group of mostly frost-sensitive woody plants in New Zealand. The results of this research verify the location of two generally mooted stadial refugia for the country and provide support for the existence of a third. A simple pattern of chloroplast haplotype diversity was recorded in extra-refugial areas, compared with a greater complexity in the vicinity of the identified refugia. This pattern was independently repeated in both main islands. The proposed refugia correspond to contemporary localities of high average winter temperatures. The sharing of chloroplast haplotypes between the different species ofMetrosiderosexamined suggests that there has been a history of repeated hybridization and introgression for these plants, possibly initiated by periods of refugial confinement. © 2004 The Linnean Society of London,Biological Journal of the Linnean Society, 2004,83, 399–412. [ABSTRACT FROM AUTHOR]

Molecular studies were conducted on Metrosideros excelsa to determine if the current genetic models for flowering with regard to inflorescence and floral meristem identity genes in annual plants were applicable to a woody perennial. MEL, MESAP1 and METFL1, the fragments of LEAFY ( LFY), APETALA1 ( AP1) and TERMINAL FLOWER1 ( TFL1) equivalents, respectively, were isolated from M. excelsa. Temporal expression patterns showed that MEL and MESAP1 exhibited a bimodal pattern of expression. Expression exhibited during early floral initiation in autumn was followed by down-regulation during winter, and up-regulation in spring as floral organogenesis occurred. Spatial expression patterns of MEL showed that it had greater similarity to FLORICAULA ( FLO) than to LFY, whereas MESAP1 was more similar to AP1 than SQUAMOSA. The interaction between MEL and METFL1 was more similar to the interaction between FLO and CENTRORADIALIS than that between LFY and TFL1. Consequently, the three genes from M. excelsa fit a broader herbaceous model encompassing Antirrhinum as well as Arabidopsis, but with differences, such as the bimodal pattern of expression seen with MEL and MESAP1. In mid-winter, at the time when both MEL and MESAP1 were down-regulated, GA1 was below the level of detection in M. excelsa buds. Even though application of gibberellin inhibits flowering in members of the Myrtaceae, MEL was responsive to gibberellin with expression in juvenile plants up-regulated by GA3. However, MESAP1 was not up-regulated indicating that meristem competence was also probably required to promote flowering in M. excelsa. [ABSTRACT FROM AUTHOR]